You are supposed to apply via the embassy in the jurisdiction where you are physically located. So if you are physically in Vietnam, you apply via one of the two embassies/consulates in Vietnam. You should only apply via your home country if you are actually in your home country.
Also, the 5th was a holiday, so only been 7 days. LA states 15, and if they ask for additional documents, they add 5 more days once those documents are submitted
I think this was meant to include the other John who responded to you. I think what he is saying though, if you keep telling the embassy that you will be there for less than six months, they will keep giving you a tourist visa instead of DTV.